Integration of photonic devices with silicon IC chips makes it possible to combine the advantages of each. Among photonic devices, GaAs/AlGaAs multiple quantum well (MQW) modulators are particularly beneficial as input/output (I/O) elements on IC chips because they have a high absorption coefficient of light and can serve as both receivers and transmitters. They typically operate at an optical wavelength (.lambda.) of 850 nm (nanometers).
The aforementioned applications Ser. No. 083,784, filed Jun. 25, 1993, Ser. No. 08/236,307, filed May 2, 1994, and Ser. No. 08/366,864 filed Dec. 30, 1995, disclosed methods of bonding a photonic element, such as a GaAs/AlGaAs (MQW) modulator, to an IC chip by bonding their respective terminals to each other, filling the interiors between them with photoresist or a photoresisting cement, and then removing the substrate of the photonic device. Ser. No. 08/366,864 specifically discloses wicking a cement, such as epoxy into the interstices in place of the photoresist. However, voids that extent to one or both substrates sometimes form in the cement. These may allow that etch that removes the substrate on the modulator to affect other parts of the combined unit.